This invention relates generally to gas turbine engines, and more particularly, to methods and apparatus for monitoring gas turbine engines.
Gas turbine engines typically include a compressor section, a combustor section, and at least one turbine section. The compressor compresses air which is mixed with fuel and channeled to the combustor. The mixture is then ignited generating hot combustion gases. The combustion gases are channeled to the turbine which extracts energy from the combustion gases for powering the compressor, as well as producing useful work to power a load, such as an electrical generator, or to propel an aircraft in flight.
Gas turbine engines operate in many different operating conditions, and stable combustion facilitates engine operation over a wide range of engine operating conditions. More specifically, stable combustion facilitates reducing engine blowout while achieving engine rated thrust or power levels. Furthermore, for gas turbines operated with dry low nitrous oxide (DLN) techniques, combustion stability also facilitates controlling nitrous oxide (NOx) and carbon monoxide emissions. While using DLN techniques facilitates generating a reduced quantity of NOx, the lean fuel/air mixture supplied to the gas turbine may also cause combustion instabilities, such as oscillations, which may result in mechanical failures and/or shutdowns. Relatively high oscillation frequencies may cause combustor fatigue thereby reducing the service life of the combustor, or may also cause other hot gas path components to fail.
To facilitate reducing potentially harmful combustion resonance, frequent inspections of the gas turbine are performed to determine whether the combustion dynamics have reached a level where component damage is more probable. For example, temporary transducers can be attached to the combustor to enable dynamic measurements to be made during tuning. However, once the transducers are removed, direct combustion dynamics information is not available to the operator until the next scheduled tuning.